There are various types of ring binders available with the most common employing three separable ring assemblies spaced at fixed locations on a metal backing member. Front and rear covers extend from a backing strip which is typically riveted to the backing member. The ring assemblies usually have complementary arcuate ring halves, having fixed ends anchored to the backing member. Typically, a spring assembly is included for biasing the opposing ring halves into engagement. The ring halves are separable into an open locked position when sheets are added to or removed from the binder. In some binders, the rings may be separated by pulling on the opposite ring halves while in others a pressure element, acting through the backing member and having handles disposed at one or both ends of the backing member may be provided to effect release.
In U.S. Pat. No. 3,074,744 to Pucci et al, a book has a back and a pair of separate hinges, which are strips with beaded edges. Two side covers are provided, each having a beaded edge with a channel extending its entire length. A slot is provided in the covers and a pair of slots provided in the back within which a hinge beaded edge is located to attach the covers to the back. This allows the covers to be removed if damaged due to cold weather by sliding in or out from the ends.
Removable covers have not been used commercially in ring binders due to the simplicity of the unitary back and covers. With the covers attached to the backing, simply riveting the back to the ring separator provides a completed binder. However, removable covers have the advantage of providing an easy way to change covers to match subject matter or to change them to a different ring separator mechanism. The means for accomplishing this described in Pucci has the disadvantage of requiring a multiplicity of parts to produce the binder. For example, as shown in FIG. 3 of Pucci, a ring separator is attached to the back, there are two separate hinges and then two separate covers which must be attached to produce the book. Also, there are no means to prevent the covers from sliding out of the beaded edge for example when griped or when placed on a shelf. Consequently, such a binder has not gained favor in the industry.